kOS, or Kerbal Operating System, is a community-supported
mod for the popular game
Kerbal Space Program

kOS is an autopilot you script yourself. kOS is to
programming, what Kerbal Space Program itself is to rocket science.
You don’t have to know what you’re doing to get started, but
you may find yourself learning a lot by accident as you play
with it. And if you already know a lot about the topic, it will
still be able to hold your interest. kOS is meant to scale
with the skill level of the user. You can start off doing very
small simple things with it, and get more and more into using its
features as you go.

kOS introduces a few new parts that each contain a simulated
computer capable of running programs written in its own scripting
langauge called kerboscript. The computer has powerful
smarts built in to the hardware that allow it to do complex
spacecraft operations in one command, thus making it possible to
make complex programs with only a few lines of script text.

The intent of kOS is to be a fully in-game item that lives
inside the Kerbal’s universe. The program isn’t running on
your own gaming computer, but rather it’s being run in a
virtual machine that is simulated in the underlying Unity engine.

There is a quickstart tutorial for people new to kOS that
gets you off the ground with a very simple launching script,
sufficient to be an introduction for people new to the mod.
Go ahead and give it a try.

kOS was originally begun as a mod by a single author, Kevin Laity aka Nivekk.
Although the project has undergone massive changes since then and now has
a very different underlying archetecture and is under active development
by a different set of people, none
of that would have been possible without his original vision and work.